JPH08290185A - Sewage purifying tank - Google Patents

Abstract

PURPOSE: To reduce the required amount of washing water and power consumption for backward washing the carrier bed by dividing a carrier bed of a biological filtration vessel into an upper carrier bed and a lower carrier bed, providing the lower carrier bed with a backward washing means and placing a treated water vessel having a larger volume than the volume of the lower carrier bed at a higher level than that of the boundary section between the upper and lower carrier beds. CONSTITUTION: In this tank, a biological filtration vessel 10 is provided with an upper carrier bed 29 and a lower carrier bed 30. Each of the carrier beds 29 and 30 is formed by packing a space partitioned by perforated plates with a granular carrier 16 on which aerobic microorganisms are deposited. Also, an air diffusing member 11 is disposed in the lower part of the upper carrier bed 29 to discharge air for biological treatment from the member 11. On the other hand, another air diffusing member 20 for jetting air out only at the time of backward washing the lower carried bed 30 is disposed in the lower part of the bed 30. At the time of performing the normal operation, the make-up SS is supplied without shaking the granular carrier 16 of the lower carrier bed 30. Further, a treated water tank 12 having a larger volume than the volume of the lower carrier bed 30 is placed at a higher level than that of the boundary section 31 between the carrier beds 29 and 30. Thus, the lower carrier bed 30 can sufficiently be washed backward without lowering the water level of the biological filtration vessel 10 to the level of the boundary section 31 or below.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sewage purification tank incorporating a biological filtration method for treating waste water.

[0002]

2. Description of the Related Art A conventionally used sewage purification tank will be described with reference to FIG. The sewage purification tank 28 includes an anaerobic filter bed tank first chamber 3, an anaerobic filter bed tank second chamber 7, a biological filter tank 10, and a partition wall.
It is divided into a treated water tank 12 and a disinfection tank 13, and contact materials are provided in the anaerobic filter bed first chamber 3 and second chamber 7, respectively. Further, a carrier bed filled with the granular carriers 16 is arranged in the biological filtration tank 10 so that biological filtration can be performed.

The water to be treated 1 enters the anaerobic filter bed tank first chamber 3 through the inflow port 2, and is subsequently advected to the anaerobic filter bed tank second chamber 7-biological filter tank 10-treated water tank 12-disinfection tank 13. It is supposed to do. And in the biological filtration tank 10, the granular carrier 1
Microorganisms are attached to 6 and biological decomposition of organic matter in wastewater and physical filtration of SS are performed at the same time. Therefore, when the sewage purification tank 28 is continuously operated, the biological filtration tank 10 is gradually blocked by SS. In order to remove the SS from the biological filtration tank 10, it is necessary to temporarily stop the normal operation and backwash the water 1 to be treated in the treated water tank 12 with a pump or the like to backwash the granular carrier 16.

[0004]

However, in order to backwash the granular carrier 16, a large amount of washing water is used in the treated water tank 1.
2 needs to be stored, and a pump with high power is required for good backwashing. Therefore, an object of the present invention is to provide a sewage purification tank that reduces the amount of cleaning water (reserved water in the treated water tank) used for backwashing the granular carrier 16 and that requires less power.

[0005]

The sewage purification tank of the present invention comprises:
In the septic tank in which the inside of the tank is partitioned by the partition wall, the anaerobic filter bed tank having the inlet 2 is provided, the biological filter tank 10, the treated water tank 12, and the disinfection tank 13 having the outlet 15 are arranged, The chamber 3 and the second chamber 7 are divided and provided with contact materials 4 respectively,
The upper carrier bed 2 is a carrier bed in which the biological filtration tank 10 has porous plates on the upper and lower sides, and the spaces partitioned by the porous plates are filled with the granular carriers 16.
9 and the lower carrier bed 30 are arranged in two stages, air diffusers are provided under the upper and lower carrier beds, respectively, and a boundary portion 31 between the upper carrier bed 29 and the lower carrier bed 30 and the anaerobic filter bed first chamber 3 is connected to the upper part by a cleaning drainage pipe 21 having a transfer pump 26, and the treated water tank 12 volume of a portion above the boundary 31 between the upper carrier bed 29 and the lower carrier bed 30 is the lower carrier bed. It is characterized by having a capacity of more than 30.

The transfer pump here may be an air lift type pump or a submersible pump as long as it can transfer water. Further, a boundary portion 31 between the upper carrier floor 29 and the lower carrier floor 30
The volume of the treated water tank 12 above the height of the point indicates the volume between the boundary portion 31 and the outflow port 15 in the treated water tank 12.

The air diffusing members 11 and 20 provided under the upper carrier bed 29 and the lower carrier bed 30, respectively, send air to the air diffusing members 11 corresponding to the upper carrier bed 29 in order to promote biological decomposition. On the other hand, the air diffusing member 20 corresponding to the lower carrier bed 30 does not operate during normal operation, but operates only during backwashing.

[0008]

In the present invention, the carrier bed installed in the biological filtration tank 10 is divided into two stages so that most of SS is collected in the lower carrier bed 30, and the lower carrier bed 30 is mainly reversed. Means for avoiding blockage by washing are used. Further, by providing a treated water tank having a capacity larger than that of the lower carrier bed 30 above the boundary portion 31, it is possible to completely replace the treated water in the lower carrier bed 30 and to perform sufficient cleaning. There is.

[0009]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a plan view and a sectional view of a sewage purification tank of the present invention. The treated water 1 is supplied from the inflow port 2, enters the anaerobic filter bed first chamber 3, and coarse solids are removed by the contact material 4. At the same time, anaerobic decomposition and denitrification are performed by the returned treated water. Be done. The space above the contact material 4 has a flow rate adjusting function for absorbing fluctuations of the inflow, so that the contact material is preferably fixed at a position not higher than the middle of the height of the anaerobic filter bed first chamber 3. The returned treated water means the treated water returned from the treated water tank 12 to the anaerobic filter bed first chamber 3 through the anaerobic filter bed circulation pipe 32.

The anaerobic filter bed first chamber outflow 8 whose flow rate is adjusted by the anaerobic filter bed first chamber 3 is transferred to the anaerobic filter bed second chamber 7 by the transfer pump 6. Here, the organic substances that could not be decomposed in the anaerobic filter bed first chamber 3 are decomposed and further denitrification is performed, and then the anaerobic filter bed second chamber effluent 9 is naturally flown to the upper part of the biological filter tank 10. Be transferred.

In the biological filtration tank 10, a carrier bed filled with a granular carrier 16 having aerobic microorganisms adhered in a space partitioned by a perforated plate is arranged in upper and lower two stages. Air diffusers 11 and 20 are installed in the lower part of each carrier bed, and the air diffuser 11 below the upper carrier bed 29 discharges air necessary for biological treatment of aerobic microorganisms. ing. Therefore, in the upper carrier bed 29, although organic substances are decomposed and ammonia is nitrified, SS is rarely supplemented by bubbling due to air discharge (granular carrier rocks due to air bubbles).

On the other hand, the diffusing member 20 below the lower carrier floor 30 is
Since air is jetted only during backwashing, SS can be sufficiently supplemented without rocking of the granular carrier during normal operation. Further, in the lower carrier bed 30, the treated water flowing down from the upper carrier bed 29 sufficiently contains air even if air is not supplied from the air diffusing member 20 below the lower carrier bed 30, so that organic matter is decomposed and decomposed. It is possible to carry out nitrification of ammonia.

The water to be treated by the above treatment steps is
Since the organic matter, SS, and nitrogen are sufficiently removed, the treated water becomes highly transparent and highly advanced, and is transferred to the treated water tank 12 and sterilized in the disinfection tank 13 and discharged as the post-treated water 14 from the outlet 15.

Next, the operation during normal operation and during backwash will be described with reference to FIG. FIG. 2A shows the processing status during normal operation. As described above, the biological carrier tank 10 is provided with the upper carrier bed 29 and the lower carrier bed 30, and the air diffusing members 11 and 20 are provided at the lower part of each. A cleaning drainage pipe 21 connected to the upper part of the anaerobic filter bed first chamber 3 is provided at a boundary portion 31 between the upper carrier bed 29 and the lower carrier bed 30. The cleaning drainage pipe 21 has a transfer pump 26 for pulling out the water in the biological filtration tank 10, and the biological filtration tank 10 and the treated water tank 12 communicate with each other through an opening 22 provided in the lower portion. .

Water to be treated 23 from the second chamber 7 of the anaerobic filter bed tank
Are transferred to the upper carrier bed 29 installed in the biological filtration tank 10. The granular carrier 16 of the upper carrier bed 29 is the diffusing member 1
It is filled so as to be swung by the air bubbles discharged from No. 1 so that the air bubbles spread over the entire upper carrier bed 29. Aerobic microorganisms are attached to the granular carrier 16, and the air from the diffuser member 11 (actually oxygen in the air)
Thereby, biological treatment (BOD decomposition) and nitrification of the water 23 to be treated progress. However, the supplement of SS is the aeration member 11
It cannot be completely performed by discharging air from.

Therefore, the lower carrier bed 30 is sufficiently supplemented with SS, and the biological treatment of the treated water 23 (BOD) is performed.
Decomposition) and nitrification. As mentioned above, the lower carrier bed 3
The air diffusing member 20 provided in the lower part of FIG. 0 discharges air only during backwashing, so the granular carrier 16 in the lower carrier bed 30 during normal operation is
Is stationary. Therefore, sufficient supplement of SS can be performed. The biological treatment (BOD decomposition) and nitrification of the treated water 23 progresses because dissolved oxygen is carried over from the upper carrier bed 29.

FIG. 2 (b) is a sectional view of the vicinity of the biological filtration tank for explaining the situation during backwashing. When the normal operation is shifted to the backwash operation, air diffusion is started from the air diffusion member 20 below the lower carrier floor 30. Granular carrier 16 filled in the lower carrier bed 30
Oscillates due to air diffusion to separate SS between the granular carriers 16. At this time, the cleaning drainage pipe 21 having one end connected to the boundary portion 31 between the upper carrier floor 29 and the lower carrier floor 30 is used for S
The cleaning wastewater containing S is drawn into the anaerobic filter bed first chamber 3.
An air-lift pump is preferable for drawing out the cleaning waste water because of its structure, but another submersible pump or the like can be used.

The cleaning wastewater drawn out from the cleaning wastewater discharge pipe 21 contains SS contained in the lower carrier bed 30 and SS contained in the upper carrier bed 29 as the water level in the biological filtration tank 10 is lowered.
The amount of SS is, of course, the amount of S discharged from the lower carrier bed 30.
Since there is more S, backwashing of the lower carrier bed 30 becomes important in the present invention. During backwashing, since the diffusing member 20 under the lower carrier bed 30 diffuses air, SS is likely to be dispersed throughout the lower carrier bed 30, and in order to efficiently remove SS, the lower carrier bed 30 Extrusion flow from below is preferred. And
In order to sufficiently remove the SS, treated water of a volume equal to or larger than that of the lower carrier bed 30 is required.

In the present invention, since the treated water having a capacity equal to or larger than that of the lower carrier bed 30 is secured in the treated water tank 12, SS can be sufficiently removed. Furthermore, since the treated water having a capacity equal to or larger than that of the lower carrier bed 30 is secured above the boundary portion 31 to which the cleaning drainage pipe 21 for pulling out the cleaning drainage is connected, the water level of the biological filtration tank 10 is increased. Sufficient backwash can be performed without lowering than the boundary. As for the required power of the pump, since the wash water is secured above the boundary where the wash waste water is drawn out, the potential energy can be effectively utilized and only a small power is required.

FIG. 3 shows an embodiment in which the treated water tank 12 is made more compact in accordance with the present invention. In this case, the biological filtration tank 10 and the treated water tank 12 are communicated with each other through the opening 22 at the bottom, as in FIG.
The capacity of the treated water tank 12 below 1 is greatly reduced.

[0021]

As described above, according to the present invention, the amount of washing water in the biological filtration tank can be reduced and sufficient SS can be discharged. Along with this, the treated water tank can be made smaller and the entire wastewater purification tank can be made compact. Also, the pump used during backwashing can be handled with a small required power.

[Brief description of drawings]

FIG. 1 is a drawing for explaining a wastewater purification tank of the present invention, in which (a) is a plan view and (b) is a sectional view taken along line AA.

FIG. 2 is a sectional view of a biological filtration tank for explaining an embodiment of the present invention, (a) shows a normal operation, and (b) shows a backwash operation.

FIG. 3 is a sectional view of a biological filtration tank showing another embodiment according to the present invention.

FIG. 4 is a sectional view of a conventionally used sewage purification tank.

[Explanation of symbols]

1. Water to be treated 2. Inlet 3. Anaerobic filter bed first chamber 4. Contact material 5. Volume part 6. Transfer pump
7. Anaerobic filter bed second chamber 8. Anaerobic filter bed first chamber runoff water 9. Anaerobic filter bed second chamber runoff water 10. Biological filtration tank 11. Air diffuser 12. Treated water tank 13. Disinfection tank 14. Treated water 15. Outlet 16. Granular carrier 17. Perforated plate 18. Perforated plate
19. Perforated plate 20. Air diffuser 21. Cleaning drainage pipe 22. Opening 23. Water to be treated 24. Wash water 25. Treated water 26. Transfer pump 27.
Wash drainage 28. Sewage septic tank 29. Upper carrier floor
30. Lower carrier bed 31. Boundary 32. Anaerobic filter bed circulation pipe

Claims (1)

[Claims] Claim: What is claimed is: 1. A anaerobic filter bed tank is partitioned by a partition wall to dispose an anaerobic filter bed tank having an inflow port, a biological filtration tank, a treated water tank, and a disinfection tank having an outflow port.
The upper and lower carrier beds are carrier beds which are divided into a chamber and a second chamber and are provided with respective contact materials, and the biological filtration tank has upper and lower porous plates and the spaces partitioned by the porous plates are filled with granular carriers. Cleaning and drainage which is arranged in two stages, and which has air diffusing members provided under the upper and lower carrier beds, respectively, and which has a transfer pump between the boundary between the upper carrier bed and the lower carrier bed and the upper part of the first chamber of the anaerobic filter bed tank. A sewage purification tank characterized in that a treated water tank capacity of a portion which is connected by a discharge pipe and is located above a height of a boundary portion between an upper carrier bed and a lower carrier bed is larger than a capacity of the lower carrier bed.